Grill surface



FIG. 1 is a perspective view of a grill surface from the front side embodying our new design;

FIG. 2 is a top plan thereof;

FIG. 3 is a side elevational view thereof; and,

FIG. 4 is a front view thereof.

The broken lines shown in the drawings are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a grill surface, as shown and described. 